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<head>
  <meta charset="UTF-8">
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  <title>Document</title>
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<body>
  <script>
    // 下面res的返回值是[2] 说法对吗
    const arr = [1,2,3]

    const res = arr.map(function(item, index) {
      return item % 2 === 0
    })

    console.log(res);
  </script>
</body>
</html>